The Clonal Selection Theory Was First Proposed in the 1950s

question 15

Multiple Choice

The clonal selection theory was first proposed in the 1950s, decades before the molecular details of B and T lymphocyte development and lymphocyte antigen recognition responses were elucidated. Nonetheless, Burnet, who proposed this theory, correctly inferred several key aspects of adaptive immune responses. One key postulate that Burnet proposed was that:

• A) Cells of the innate immune system are distinct from those of the adaptive immune system.
• B) Cells of the adaptive immune system are generated from a pluripotent hematopoietic stem cell that resides in the bone marrow.
• C) B and T lymphocytes are closely related cells that have distinct properties from myeloid cells.
• D) Circulating antibodies are generated by many different antibody-secreting cells, each of which expresses a single type of antibody on its surface as a receptor.
• E) Antibodies binding to pathogens lead to efficient pathogen clearance by phagocytic cells.

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Definitions:

Marginal Expenditure

The incremental cost associated with the purchase of an additional unit of a good or service.

Marginal Product

The increase in output that arises from an additional unit of input.

Marginal Revenue

The additional income generated from the sale of one more unit of a product or service.

Marginal Product

Marginal product is the additional output that is produced by adding one more unit of a specific input, holding all other inputs constant.